Develop Reference

Detect laser light dot of any colour using OpenCV in Android

I am trying to detect laser light dot of any colour of laser.and i have done some reference code from here OpenCV Android Track laser dot
That code is running perfectly for Only RED colour detection and i want any colour of laser dot detection.
I am new in OpenCV.
Here's what i have done till now :
Mat originalFrame= new Mat();
Mat frame = new Mat();
cvf.rgba().copyTo(originalFrame);
cvf.rgba().copyTo(frame);
Mat frameH;
Mat frameV;
Mat frameS;
mRgba = cvf.rgba();
List<MatOfPoint> contours = new ArrayList<MatOfPoint>();
Mat hierarchy = new Mat();
// Mat frameS;
// Convert it to HSV
Imgproc.cvtColor(frame, frame, Imgproc.COLOR_RGB2HSV);
// Split the frame into individual components (separate images for H, S,
// and V)
mChannels.clear();
Core.split(frame, mChannels); // Split channels: 0-H, 1-S, 2-V
frameH = mChannels.get(0);
frameS = mChannels.get(1);
frameV = mChannels.get(2);
// Apply a threshold to each component
Imgproc.threshold(frameH, frameH, 155, 160, Imgproc.THRESH_BINARY);
// Imgproc.threshold(frameS, frameS, 0, 100, Imgproc.THRESH_BINARY);
Imgproc.threshold(frameV, frameV, 250, 256, Imgproc.THRESH_BINARY);
// Perform an AND operation
Core.bitwise_and(frameH, frameV, frame);
//
// Core.bitwise_and(frame,frameS,frame);
Imgproc.findContours(frame, contours, hierarchy, Imgproc.RETR_CCOMP, Imgproc.CHAIN_APPROX_SIMPLE, new Point(0, 0));
hierarchy.release();
for ( int contourIdx=0; contourIdx < contours.size(); contourIdx++ )
{
// Minimum size allowed for consideration
MatOfPoint2f approxCurve = new MatOfPoint2f();
MatOfPoint2f contour2f = new MatOfPoint2f( contours.get(contourIdx).toArray() );
//Processing on mMOP2f1 which is in type MatOfPoint2f
double approxDistance = Imgproc.arcLength(contour2f, true)*0.02;
Imgproc.approxPolyDP(contour2f, approxCurve, approxDistance, true);
//Convert back to MatOfPoint
MatOfPoint points = new MatOfPoint( approxCurve.toArray() );
// Get bounding rect of contour
Rect rect = Imgproc.boundingRect(points);
Imgproc.rectangle(originalFrame, new Point(rect.x, rect.y), new Point(rect.x + rect.width, rect.y + rect.height), new Scalar(0, 0, 255), 3);
}

This is old question but i have findy my solution using core.InRange
Follow my alternative version
#Override
public void onCameraViewStarted(int width, int height) {
mat1 = new Mat(height, width, CvType.CV_16UC4);
mat2 = new Mat(height, width, CvType.CV_16UC4);
}
#Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
Mat src = inputFrame.rgba();
Imgproc.cvtColor(inputFrame.rgba(), mat1, Imgproc.COLOR_BGR2HSV);
//rangeLow and RangeHight is Scalar
Core.inRange(mat1, rangeLow, rangeHight, mat2);
Core.MinMaxLocResult mmG = Core.minMaxLoc(mat2);
Core.rotate(src, src, Core.ROTATE_90_CLOCKWISE);
Imgproc.circle(src,mmG.maxLoc,30,new Scalar(0,255,0), 5, Imgproc.LINE_AA);
return src;
}

The code you posted carries out two thresholding operations. One on the hue and one on the value. It then ANDs the results together. Because of the way it thresholds the hue, the effect is that it is looking for a bright red(ish) spot.
My first solution would be to look for just a bright spot (so just look on the hue frame). You might also try looking for high saturations (except that a laser spot may well overload the sensors, and result in an apparently unsaturated pixel).
To select the appropriate threshold values, you will have to experiment with various images.

Detecting circles of a color gives "image must be 8-bit single-channel in HoughCircle" error in OpenCV

I am building an Android Application and I want to be able to detect black circles. I am using OpenCV3 for Android and I am able to filter out the black colours from my camera feed using the code below. Kindly note that I used the Color-blob-detection example given in the Android SDK and tweaked the code as such:
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
mRgba = inputFrame.rgba();
if (mIsColorSelected) {
Bitmap resultBitmap;
resultBitmap = Bitmap.createBitmap(mRgba.cols(), mRgba.rows(),Bitmap.Config.ARGB_8888);
Utils.matToBitmap(mRgba, resultBitmap);
//TODO - look for circles
Mat mat = new Mat(resultBitmap.getWidth(), resultBitmap.getHeight(), CvType.CV_8UC1);
Utils.bitmapToMat(resultBitmap, mat);
final Bitmap bitmap;
//TODO - filter out the black only
Mat mHSV = mat;
Mat mHSVThreshed = mat;
Mat mRgba2 = mat;
Imgproc.cvtColor(mat, mHSV, Imgproc.COLOR_BGR2HSV, 0);
Core.inRange(mHSV, new Scalar(0, 0, 0), new Scalar(130, 130, 130), mHSVThreshed);
Imgproc.cvtColor(mHSVThreshed, mat, Imgproc.COLOR_GRAY2BGR, 0);
Imgproc.cvtColor(mat, mRgba2, Imgproc.COLOR_BGR2RGBA, 0);
Imgproc.GaussianBlur(mRgba2, mRgba2, new Size(9, 9), 2, 2);
//this is for displaying purposes only.
//At this point, the image would be black and white, where the white spots are the black detected blobs
// Bitmap bmp = Bitmap.createBitmap(mRgba2.cols(), mRgba2.rows(), Bitmap.Config.ARGB_8888);
//Utils.matToBitmap(mRgba2, bmp);
//bitmap = bmp; //resultBitmap;
//TODO - new circle detection code: this uses the colour filtered Mat
mat = mRgba2;
Imgproc.HoughCircles(mat, circles,
Imgproc.CV_HOUGH_GRADIENT, 1, minDist, 100,
20, 0, 0);
/* get the number of circles detected */
int numberOfCircles = (circles.rows() == 0) ? 0 : circles.cols();
/* draw the circles found on the image */
for (int i = 0; i < numberOfCircles; i++) {
/* get the circle details, circleCoordinates[0, 1, 2] = (x,y,r)
* (x,y) are the coordinates of the circle's center
*/
double[] circleCoordinates = circles.get(0, i);
int x = (int) circleCoordinates[0], y = (int) circleCoordinates[1];
Point center = new Point(x, y);
int radius = (int) circleCoordinates[2];
/* circle's outline */
Imgproc.circle(mRgba2, center, radius, new Scalar(0,
200, 255), 4);
/* circle's center outline */
Imgproc.rectangle(mRgba2, new Point(x - 5, y - 5),
new Point(x + 5, y + 5),
new Scalar(0, 200, 255), -1);
}
Utils.matToBitmap(mRgba2, resultBitmap);
bitmap = resultBitmap;
runOnUiThread(new Runnable() {
#Override
public void run() {
mOpenCvCameraView.disableView();
mOpenCvCameraView.setVisibility(SurfaceView.GONE);
imageView.setVisibility(View.VISIBLE);
imageView.setImageBitmap(bitmap);
}
});
}
return mRgba;
}
What my code does is that it takes a snapshot of the camera feed as a Mat, and then using that Mat, I do some image processing on it and to black out everything except the black colour. The resulting Mat is the mRgba2 variable and I converted to Bitmap and displayed on an ImageView. I displayed this Bitmap to confirm that I am getting the result I want.
After I know that I'm able to filter out the colour I wanted, I then run a GaussianBlur on it then proceed to run HoughCircles. However, when I run the
Imgproc.HoughCircles(mat, circles,
Imgproc.CV_HOUGH_GRADIENT, 1, minDist, 100,
20, 0, 0);
line, I get an
The source image must be 8-bit, single-channel in function CvSeq* cvHoughCircles(CvArr*, void*, int, double, double, double, double, int, int)
Error.
I know that the code wherein I run HoughCircles on a given mat variable works, because I tested it before. Now, changing the mat variable I feed onto it does not, and I wonder what I did differently for the code to not work.

HoughCircles runs only on grayscale (CV8U) images.
Replacing
Imgproc.cvtColor(mat, mRgba2, Imgproc.COLOR_BGR2RGBA, 0);
with
Imgproc.cvtColor(mat, mRgba2, Imgproc.COLOR_BGR2GRAY, 0);
should remove the error.
Then the problem is to detect circles of a given color. This won't pose much of a problem in your case, because you are detecting black circles anyway. Instead of black circles, this will detect dark circles.
If you have dark colors other than black in some of the circles, you can filter them out separately by looking at the pixel values in a different color space.

Opencv - FloodFill doesn't change mask image

I try to use floodFill algorithm on my android application. I click a point to select seed.Then I run floodfill algorithm. I want to show only selected area same as seed color. To do this, I display mask mat object. But it is black everytime, it doens't change. I used FLOODFILL_FIXED_RANGE and FLOODFILL_MASK_ONLY flags.
My code is here :
Imgproc.cvtColor(mRgba, temp, Imgproc.COLOR_RGBA2RGB);
Imgproc.cvtColor(temp, temp, Imgproc.COLOR_RGB2GRAY);
mMask = Mat.zeros(mMask.size(), CvType.CV_8UC1);
Imgproc.floodFill(temp, mMask, fpts.get(fpts.size()-1), new Scalar(255, 255, 255),new Rect(new Point(0,0), new Point(5,5)),new Scalar(30), new Scalar(30), Imgproc.FLOODFILL_FIXED_RANGE);
Core.circle(temp, fpts.get(fpts.size()-1), 7, new Scalar(255, 255, 255), RADIUS);
Mat temp3 = new Mat(temp.size(), mMask.type());
temp3 = mMask.submat(new Rect( 2, 2, mMask.width()-2, mMask.height()-2)) ;
Log.i(TAG, temp3.width() + "-" + temp3.height()+"**" + temp.width()+"-"+temp.height());
// / Show me what you got from template matching
Core.rectangle(temp, matchLoc, new Point(matchLoc.x + mTemp.cols(),
matchLoc.y + mTemp.rows()), new Scalar(0, 255, 0));
return temp3;
If I return temp, I can show changed input image.

You need to set the new value for the mask in the Imgproc.floodFill flags. To change the mask to white (255):
int flags = 4 + (255 << 8) + Imgproc.FLOODFILL_FIXED_RANGE;

how to detect eye pupil circularly in opencv

I am working on opencv in android and i want to change eye pupil color through Hue channel and i achieve this already but the problem is that the region i detected is in rectangle but i want this region circular as eye pupil is circular region. kindly help how i achieve this.
private Mat get_template(CascadeClassifier clasificator, Rect area,int size){
Mat template = new Mat();
Mat mROI = mGray.submat(area);
MatOfRect eyes = new MatOfRect();
Point iris = new Point();
Rect eye_template = new Rect();
clasificator.detectMultiScale(mROI, eyes, 1.15, 2,Objdetect.CASCADE_FIND_BIGGEST_OBJECT|Objdetect.CASCADE_SCALE_IMAGE, new Size(30,30),new Size());
Rect[] eyesArray = eyes.toArray();
for (int i = 0; i < eyesArray.length; i++){
Rect e = eyesArray[i];
e.x = area.x + e.x;
e.y = area.y + e.y;
Rect eye_only_rectangle = new Rect((int)e.tl().x,(int)( e.tl().y + e.height*0.4),(int)e.width,(int)(e.height*0.6));
mROI = mGray.submat(eye_only_rectangle);
Mat vyrez = mRgba.submat(eye_only_rectangle);
Core.MinMaxLocResult mmG = Core.minMaxLoc(mROI);
Core.circle(vyrez, mmG.minLoc,2, new Scalar(255, 255, 255, 255),2);
iris.x = mmG.minLoc.x + eye_only_rectangle.x;
iris.y = mmG.minLoc.y + eye_only_rectangle.y;
eye_template = new Rect((int)iris.x-size/2,(int)iris.y-size/2 ,size,size);
Core.rectangle(mRgba,eye_template.tl(),eye_template.br(),new Scalar(255, 0, 0, 255), 2);
template = (mGray.submat(eye_template)).clone();
return template;
}
return template;
}

Some potential solutions:
the simplest, although it might not be very robust is to calculate the inscribed circle (the circle bound by the rectangle) and change it's color - if your pupil detection is very accurate this solution may work fine.
a more robust solution would be to detect the area of the pupil based on color or gradient (edge detection)

haar cascade for eye ball in opencv android

I am working on opencv eye detection project and i have sucessfully detect rectangular region of both eyes through the help of haar cascade for boths eyes. now i want to detect the eye balls from both eyes, the problem is that i have no haar cascade for eye ball tracking. kindly help me if anyone of you have this xml and suggest other solution.
here is my code of eye detection
private Mat get_template(CascadeClassifier clasificator, Rect area,int size)
{
Mat eye = new Mat();
Mat template = new Mat();
Mat mROI = mGray.submat(area);
MatOfRect eyes = new MatOfRect();
Point iris = new Point();
Rect eye_template = new Rect();
clasificator.detectMultiScale(mROI, eyes, 1.15, 2, Objdetect.CASCADE_FIND_BIGGEST_OBJECT|Objdetect.CASCADE_SCALE_IMAGE, new Size(30,30), new Size());
Rect[] eyesArray = eyes.toArray();
for (int i = 0; i < eyesArray.length; i++)
{
Rect e = eyesArray[i];
e.x = area.x + e.x;
e.y = area.y + e.y;
Core.rectangle(mROI, e.tl(), e.br(), new Scalar(25, 50, 0, 255));
Rect eye_only_rectangle = new Rect((int)e.tl().x, (int)( e.tl().y + e.height*0.4), (int)e.width, (int)(e.height*0.6));
//reduce ROI
mROI = mGray.submat(eye_only_rectangle);
Mat vyrez = mRgba.submat(eye_only_rectangle);
Core.MinMaxLocResult mmG = Core.minMaxLoc(mROI);
//Draw pink circle on eyeball
int radius = vyrez.height()/2;
// Core.circle(vyrez, mmG.minLoc, 2, new Scalar(0, 255, 0, 1), radius);
//Core.circle(vyrez, mmG.minLoc,2, new Scalar(255, 0, 255),1);
iris.x = mmG.minLoc.x + eye_only_rectangle.x;
iris.y = mmG.minLoc.y + eye_only_rectangle.y;
eye_template = new Rect((int)iris.x-size/2,(int)iris.y-size/2 ,size,size);
//draw red rectangle around eyeball
//Core.rectangle(mRgba,eye_template.tl(),eye_template.br(),new Scalar(255, 0, 0, 255), 2);
eye = (mRgba.submat(eye_only_rectangle));
template = (mGray.submat(eye_template)).clone();
//return template;
Mat eyeball_HSV = new Mat();
Mat dest = new Mat();
//Mat eye = new Mat();
//eye = mRgba.submat(eye_only_rectangle);
List<Mat> hsv_channel = new ArrayList<Mat>();
//convert image to HSV
Imgproc.cvtColor(eye, eyeball_HSV, Imgproc.COLOR_RGB2HSV, 0);
// get HSV channel
//hsv_channel[0] is hue
//hsv_channel[1] is saturation
//hsv_channel[2] is visibility
Core.split(eyeball_HSV, hsv_channel);
try
{
hsv_channel.get(0).setTo(new Scalar(145));
Log.v(TAG, "Got the Channel!");
}
catch(Exception ex)
{
ex.printStackTrace();
Log.v(TAG, "Didn't get any channel");
}
Core.merge(hsv_channel, eyeball_HSV);
Imgproc.cvtColor(eyeball_HSV, dest, Imgproc.COLOR_HSV2RGB);
Imgproc.cvtColor(dest, eye, Imgproc.COLOR_RGB2RGBA);
}
return eye;
}`enter code here`

If you are willing to consider other solutions then haar cascades, you can use facial landmark detection code. Facial landmark packages can give the location of the eyes in the image (usually, center of the eye and left and right borders).
Examples of landmark detection packages:
STASM:
http://www.milbo.users.sonic.net/stasm/
Flandmark detector:
http://cmp.felk.cvut.cz/~uricamic/flandmark/